x86: restore (optional) forwarding of PCI SERR induced NMI to Dom0

c/s 22949:54fe1011f86b removed the forwarding of NMIs to Dom0 when they
were caused by PCI SERR. NMI buttons as well as BMCs (like HP's iLO)
may however want such events to be seen in Dom0 (e.g. to trigger a
dump).

Therefore restore most of the functionality which named c/s removed
(adjusted for subsequent changes, and adjusting the public interface to
use the modern term, retaining the old one for backwards
compatibility).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Keir Fraser <keir@xen.org>

1 files changed, 15 insertions, 3 deletions

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index ab4e85e1f5..a97033d1a6 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -3089,6 +3089,7 @@ static void nmi_mce_softirq(void)
 static void pci_serr_softirq(void)
 {
     printk("\n\nNMI - PCI system error (SERR)\n");
+    outb(inb(0x61) & 0x0b, 0x61); /* re-enable the PCI SERR error line. */
 }
 
 void async_exception_cleanup(struct vcpu *curr)
@@ -3135,9 +3136,20 @@ static void pci_serr_error(struct cpu_user_regs *regs)
 {
     outb((inb(0x61) & 0x0f) | 0x04, 0x61); /* clear-and-disable the PCI SERR error line. */
 
-    /* Would like to print a diagnostic here but can't call printk()
-       from NMI context -- raise a softirq instead. */
-    raise_softirq(PCI_SERR_SOFTIRQ);
+    switch ( opt_nmi[0] )
+    {
+    case 'd': /* 'dom0' */
+        nmi_dom0_report(_XEN_NMIREASON_pci_serr);
+    case 'i': /* 'ignore' */
+        /* Would like to print a diagnostic here but can't call printk()
+           from NMI context -- raise a softirq instead. */
+        raise_softirq(PCI_SERR_SOFTIRQ);
+        break;
+    default:  /* 'fatal' */
+        console_force_unlock();
+        printk("\n\nNMI - PCI system error (SERR)\n");
+        fatal_trap(TRAP_nmi, regs);
+    }
 }
 
 static void io_check_error(struct cpu_user_regs *regs)